Novel nonionic photoacid generator releasing strong acid for chemically amplified resists

Recently we have developed a novel non-ionic PAG, which generates a strong acid (perfluorobutanesulfonic acid) by light irradiation, and is applicable for chemically amplified photoresists. Application-relevant properties such as solubility in common organic solvents and water, thermal stability, storage stability in neat form and solution, UV absorption, and sensitivity in model formulations were evaluated. The compound showed good solubility in organic solvents and no solubility in water. Good storage stability was observed in solution, even in the presence of amine, where conventional non-ionic PAGs were not found to be stable. From the evaluation in the model formulation with ArF laser exposure, it was found that this new compound has high transparency at 193 nm and superior photo-efficiency to triphenylsulfonium perfluorobutanesulfonate (TPSPB). In addition, the new compound exhibited significant sensitivities at DUV (254 nm) and i-line (365 nm) wavelengths.